KABUL, Afghanistan — Vice President Joe Biden was in Afghanistan on Monday for a surprise visit aimed at assessing progress in handing over security from foreign to Afghan forces, a key issue that comes against a backdrop of mounting concerns in the U.S. over the gains made in the nearly decade-long war.

The U.S. is to begin withdrawing combat forces from Afghanistan in July, and questions remain about the ability of the country’s security forces to take up the fight in the face of a virulent insurgency. NATO hopes Afghan forces will assume full responsibility for security by 2014.

Just a month ago, President Barack Obama came to Afghanistan telling U.S. forces in the country they are making progress in their mission to defeat terrorism. American troops comprise the bulk of the 140,000-strong NATO force that has been battling the Taliban.

31 dead in Acapulco in four days

ACAPULCO, Mexico — Police said a man has been slain on a main highway leading into Acapulco, bringing to 31 the number of people killed in the Pacific coast resort city over four days.

Guerrero state Investigative Police Director Fernando Monreal Leyva says the unidentified man was shot several times in the head and found on the road with his shirt pulled over his face.

Leyva said Monday that federal, state and local police are meeting with the military to consider ways to beef up security in Acapulco, where 27 people were killed in less than a day over a particularly blood weekend.

Iran claims it infiltrated Israel spy agency

TEHRAN, Iran — Iran’s intelligence services said Monday they have arrested suspects in the assassination a year ago of a nuclear physicist in a months-long covert operation that also led them to penetrate Israel’s Mossad spy agency.

Iran blames the Mossad for the slaying of Tehran University physics professor Masoud Ali Mohammadi, who was killed by a bomb-rigged motorcycle that exploded outside his house as he was leaving for work in January 2010. Possible explanations for why he was targeted have never been clear, particularly as he had no known link to Iran’s nuclear work.